FIELD OF THE INVENTION
This invention relates to the structure of a bar-shaped torsion spring, such as a torsion bar or a stabilizer.
According to previously known methods, a bar-shaped torsion spring of this sort is formed as a whole, solid body. The linking portions at its both ends, for instance in the case of a stabilizer, are pressed down to be made into flat shape, and, thereafter, linking holes are pierced therein. Otherwise, with a torsion bar, the linking portions are merely made into hexagonal shape. Therefore, the weight tends to be too heavy. Furthermore, since the bar-shaped torsion spring is a relatively long body, handling is not easy for the processing or fixing of linking portions to both ends. Further, various problematical points exist in regards to its performance. In order to make the spring lighter in weight, it has been proposed to make such a spring into pipe shape. However, it has been feared that, in this instance, the strength of the linking portions at both ends has not been sufficient, in some cases, to avoid breakage or damage.